Therapeutic lamp emitting polarized light

ABSTRACT

Therapeutic lamp emitting polarized light, comprising a housing of three consecutive parts which define a common interior space, the first part being a handle having a substantially tubular form, the second part being a dome-shaped middle portion attached to an end of the handle, and the third part being a cylindrical frontal portion attached to the middle portion, the frontal portion having an axis which forms a first obtuse angle with the axis of the handle. A light source assembly with closed inner space is arranged in the interior of the housing spaced from the internal walls thereof so that an air passage channel is formed around the assembly, the assembly comprising a pair of mutually attached cylindrical tubes with axes forming a second obtuse angle being close to the first obtuse angle, a light bulb with an electrical power of at most 100 W and a reflector being attached to the first tube, a polarizer placed in the path of the light emitted by the bulb, a light filter plate for filtering out ultraviolet spectral components from the emitted light attached to the second tube, a fan being arranged in the handle to suck fresh air through the channel around the whole mantle surface of the assembly, the handle comprising slots for letting the air flow out from the inner space.

The invention relates to a therapeutic lamp, emitting polarized light,which comprises a housing which has a handle built integrally with thehousing, a light bulb with an electrical power of at most 100 W arrangedin the housing, a reflector arranged immediately behind the bulb, alight filter plate and a fan arranged in the housing behind thereflector.

A therapeutic lamp of the above defined type is known e.g. from thepublished international patent application No. WO 84/03049.

The biostimulating effects of polarized light are disclosed in theGerman patent specification No. DE-PS 32.20.218-C2 issued to M. Fenyo etal. FIG. 5 of this patent specification shows a therapeutic lamp, inwhich a polarizer filter is used. This filter is effective in thevisible range of wavelengths only, therefore the infrared spectralcomponents are filtered out. The lamp is capable of providing an outputlight bundle of parallel rays which has a circular cross section with adiameter of about 50 mm and the power consumption of the lamp is 150 W.This lamp substantially generates heat and a fan is used for cooling.All optical elements are arranged in a row one before the other. Owingto the high operational temperature of the casing a separate supportingstructure is used.

It can be said that the lamp according to the above mentionedpublication No. WO 84/03049 represents a more improved design. Here aBrewster-type polarizer is used which is effective also in the infraredrange of wavelengths. Owing to the utilization of the infrared spectralcomponents of the bulb a substantial reduction of the required lamppower could be attained. The use of a Brewster-type polarizer requiresthat the passageway of the light beams be tilted in a predeterminedangle, in which the direction of the output beams close an angle of 114°(the twice of Brewster's angle) with the main direction of the lightsource. This requirement substantially affects the form of such lamps.In the above referred type of the lamp a substantially cylindrical casewas used which comprised a separate handle portion and an obliquelydirected frontal portion. In the frontal portion specific filterelements and a glass plate were provided to prevent the surface of thepolarizer from the dust present in the sucked-in air. The cooling of thecase was designed in such a way that the casing remained substantiallyopen which could not safely prevent the sensitive light reflecting ortransmitting surfaces from getting dusty with time.

The use of a large and long cylindrical casing with a separate handlemade the handling of the lamp difficult, since the supporting hand hadto bear not only the weight of the device but also the torque whichlatter became more apparent when the treatment was wholly or in partdownwardly directed.

The expected life-time of a metal halogen bulb is generally about 200hours and an inappropriate cooling can even shorten this value.

The main object of the invention is to provide an improved therapeuticlamp emitting polarized light which can be used more comfortably, has animproved protection against dust and which has a more effective cooling.

Further objects of the invention lie in the extension of the expectedlife-time of the bulb and in the improvement of the biostimulatingeffects.

According to the invention a therapeutic lamp emitting polarized lighthas been provided which comprises a housing, a handle built integrallywith the housing, a light bulb with an electrical power of at most 100 Warranged in the housing, a reflector arranged immediately behind thebulb, a polarizer placed in the path of the light emitted by the bulb, alight filter plate for filtering out ultraviolet spectral componentsfrom the emitted light and a fan arranged in the housing behind thereflector, and the improvement according to the invention lies in thatthe housing comprises three consecutively and directly attached partswhich define a common interior space, the first part is the handlehaving a substantially tubular form with an axis, the second part is adome-shaped middle portion attached at one end to an end of the handle,and the third part is a cylindrical frontal portion attached to an otherend of the middle portion, the frontal portion has an axis which closesa first obtuse angle with the axis of the handle, a light sourceassembly with closed inner space is arranged in the interior of thehousing spaced from internal walls thereof so that an air passagechannel is formed around the assembly, the assembly comprises a pair ofmutually attached cylindrical tubes with axes closing a second obtuseangle being close to the first obtuse angle, the bulb and the reflectorare attached to the first tube, the polarizer is arranged in theassembly, the assembly comprises light diverting means to divertselected portion of the outgoing light of the bulb towards the secondcylinder, the fan is arranged in the handle to suck fresh air throughthe channel around the whole mantle surface of the assembly, the handlecomprises slots for letting flowing air out from the inner space.

In a preferable embodiment the light diverting means is a Brewsterpolarizer, the second obtuse angle is twice the Brewster's angle, thetubes are cut by a plane having a normal closing Brewster's angle withboth of the axes, and the polarizer comprises a plurality of spacedglass plates attached to the cut plane.

It is preferable if the filter plate closes the second tube.

The cooling will be at optimum if the assembly is arranged in the middleand frontal portions of the housing so that the spacing around theassembly will be greater close to the polarizer and narrower close tothe reflector.

It is preferable if the angle between the axis of the handle and of thefrontal portion of the housing is between 105° and 120°.

The holding of the therapeutic lamp will be more convenient if thehandle has finger receiving depressions at the outer perimeter facingopposite direction relative to the mouth opening of the frontal portion.

The outflowing air cannot disturb the user if the slots of the handleare provided at the lower end thereof.

In a preferable embodiment of the polarizer the glass plates haveelliptical forms and a metal closing plate of the same form is providedwhich is spaced from the rearest one of the glass plates and it isabutting the cut plane of the tubes, and the closing plate is paintedblack at both sides.

In a preferable embodiment the bulb is a metal halogen one builttogether with the reflector and in operation it is under-heated at mostby 5%.

The invention will now be described in connection with a preferableembodiment thereof, in which reference will be made to the accompanyingdrawings. In the drawing:

FIG. 1 shows the sectional elevation view of an embodiment of thetherapeutic lamp according to the invention;

FIG. 2 shows the side view of the therapeutic lamp;

FIG. 3 shows the front view of the therapeutic lamp;

FIG. 4 shows the front view of an obliquely held therapeutic lamp;

FIG. 5 shows the perspective view of the internal light source assembly;and

FIG. 6 shows an enlarge detail of the Brewster-polarizer in sectionalview.

Therapeutic lamp 1 shown in FIG. 1 comprises three main constructionalparts i.e. housing 2, light source assembly 3 and fan 4. The housing 2includes handle 21, a dome-shaped middle portion 22 and a frontalportion 23. The form of these housing parts can well be observed inFIGS. 1 to 4. The housing 2 consists preferably of a pair of conformingplastic halves which define a cavity for receiving the otherconstructional parts.

Light source assembly 3 is arranged concentrically in middle and frontalportions 22, 23 of the housing 2 as shown in FIG. 1, in such a way thatthe perimeter of the assembly 3 is always spaced from the interior wallof the housing 2. The term "concentric" intends to express that thespacing, when measured in a plane normal to that of FIG. 1, issubstantially uniform. FIG. 1 shows that the light source assembly 3 isnot equally spaced in the plane of the drawing.

The light source assembly 3 comprises a pair of cylindrical tubes 31, 32made preferable from a metal like steel welded together and the axes ofthe tubes close an angle of 114° which corresponds to the twice ofBrewster's angle. The rear part of the tubes 31, 32 is cut by a planeand the elliptic sectional surface is covered by Brewster polarizer 33.The perspective view of the light source assembly 3 can be observed inFIG. 5.

FIG. 6 shows a detail of the polarizer 33 in section. The Brewsterpolarizer 33 comprises a plurality (e.g. five) of plano-parallelelliptical glass plates 34 which are spaced from one-another. At therear part of the glass plates 34 an elliptical closing plate 35 isprovided which is made preferably of a metal sheet and the closing plateis attached to the tubes 31, 32 so that a sealing is provided betweenthem. For providing an improved heat transfer both surfaces of theclosing plate 35 are painted black. The spacing between the glass plates34 and between the upper plate and the closing plate 35 as well asbetween the lower glass plate and the elliptical supporting surface ofthe tubes 31, 32 is provided by thin plastic stripes.

At the rear end portion of the tube 31 a bulb 36, preferably a metalhalogen bulb is provided which is built together with a reflector, andthe forward rim of the reflector is pressed to a ring formed depressionof the tube 31 so that a sealing is provided therebetween. The bulb 36emits light mainly in axial direction which includes visible andinfrared components and this light falls on the Brewster polarizer 33with an angle of incidence of 57°. The power of the bulb is about 20 Wbut it is at any case lower than about 80-100 W, because the coolingconditions are at optimum below this limit only. The glass plates 34 ofthe Brewster polarizer 33 reflect the light to the direction of the axisof the second tube 32 and this reflected light is linearly polarized.The non-reflected light components fall on the black internal surface ofthe closing plate 35 and the generated heat is lead away by the coolingair.

The internal cavity of the light source assembly 3 is closed and sealedby yellow light filter plate 37 at the frontal end of the tube 32. Thetask of the light filter plate 37 is on the first hand to suppressspectral components falling below about 400-450 nm of the outgoing lightof the therapeutic lamp 1 and on the other hand to seal and close theinterior of the light source assembly 3, whereby the optical propertiesof the elements of the assembly will not be affected by any dust thatwould otherwise be collected thereon.

An electrical circuit board 38 is arranged near the rear end of the bulb36 which is kept in the sketched position by means of distance membersattached to the housing 2 (not shown in the drawing). The circuit boardis adapted to receive internal end of a connection cord, to hold a fuseand a few number of electrical components. It can be preferable if anelectrical resistance or other attenuation member is connected in serieswith the bulb 36 to provide an underheating of about 2 to 5%. The slightunderheating of the bulb 36 increases the expected life time thereof andshifts the spectral distribution of the emitted light towards theinfrared range (by decreasing the effective light-temperature), wherebythe depth of penetration of the emitted light in the treated tissueswill be increased. It is also possible that such a distribution is morefavorable for biostimulation as well. The decrease of thelight-temperature might reduce the power consumption. The underheatingof the bulb 36 can also be attained by decreasing the applied supplyvoltage. If the nominal voltage of the bulb is e.g. 12 V, then theoutput voltage of a transformer feeding the bulb can be dimensioned todeliver about 11-11.4 V.

The fan 4 extends in axial direction with in the handle 21 and it sucksair through frontal inlet ring slot 24 (FIG. 3) in the space surroundingthe light source assembly 3 in the housing 2. The air leaves the innerspace of the housing through slots 25 (FIGS. 1 and 4) defined in the endwall of the handle 21. The cooling air flows around the whole mantlesurface of the light source assembly 3, whereby a very effective coolingis accomplished. In FIG. 1 the airflow is illustrated by arrows.

The specific form of the housing 2 shown in detail in the drawings hasnot only aesthetically pleasing appearance but, among other things, itassists in accomplishing an effective cooling. The space around theassembly 3 has a maximum behind the closing plate 33 and at the upperend of the first tube 31 due to the doming form of the middle portion22, and the flowing rate is sufficient to take away the heat from thelarge surface of the closing plate 35, and the width of the airflowchannel decreases at the zone of the bulb 36, whereby the flowing rateincreases significantly. In channel 26 the flow rate around theparaboloid surface of the reflector will be high and an intensivecooling takes place. This cooling ensures that the operationaltemperature of the bulb 36 cannot exceed the allowed upper limit. Thetemperature of the housing 2 will never increase more than 20° C. abovethe ambient temperature.

The axis of the handle 21 is slightly slanted relative to the axis ofthe bulb 36. From this it follows that the direction of the light raysleaving the therapeutic lamp 1 close an angle of 105°-120°, preferably105°-110° with the axis of the handle 21. Such an angular dimensioningensures a very pleasant support for the lamp, in which the hand graspsthe handle in natural position when the rays are directed e.g. to theface of the subject.

The handle 21 comprises four radial depressions to receive four fingersof the subject. The recesses are arranged in the outward portion of thehandle, while the thumb of the grasping hand can rest on the inward sideof the handle. This design is optimum for self treatment which isthought to represent the most frequent use of the therapeutic lamp. Therecesses are sufficiently wide and deep to provide a pleasantengagement.

In operational position the slots 25 are directed downwardly andbackwardly so that the outflowing air cannot be disturbing for thesubject.

In an exemplary embodiment, in which the bulb is implemented by a metalhalogen bulb of 20 W power, which has a built in reflector with a mouthdiameter of 50 mm, the inner diameter of the tubes 31, 32 can also be 50mm. The therapeutic lamp emits linearly polarized light with parallelrays having a circular cross-section with a diameter of 50 mm. The lightintensity measured at 20 cm from the filter plate is about 50 mW/cm².

What is claimed:
 1. Therapeutic lamp emitting polarized light,comprising a housing, a handle built integrally with the housing, alight bulb with an electrical power of at most 100W arranged in thehousing, a reflector arranged immediately behind the bulb, a polarizerplaced in the path of the light emitted by the bulb, a light filterplate for filtering out ultraviolet spectral components from the emittedlight and a fan arranged in the housing behind the reflector, whereinsaid housing comprises three consecutively and directly attached partsdefining a common interior space, the first part being said handlehaving a substantially tubular form with an axis, the second part beinga dome-shaped middle portion attached at one end to an end of thehandle, and the third part being a cylindrical frontal portion attachedto another end of said middle portion, the frontal portion having anaxis which closes a first obtuse angle with the axis of said handle, alight source assembly with a closed inner space being arranged in saidinterior of the housing and spaced from internal walls thereof so thatan air passage channel is formed around said assembly, said assemblycomprising a pair of mutually attached cylindrical tubes with axesforming a second obtuse angle being close to said first obtuse angle,said bulb and said reflector being attached to a first one of saidtubes, said polarizer being arranged in said assembly, said assemblycomprising light diverting means to divert selected portion of theoutgoing light of the bulb towards a second one of said tubes, said fanbeing arranged in the handle to suck in fresh air through said channelaround the whole mantle surface of said assembly, said handle comprisingslots for letting air flow out of said inner space.
 2. The therapeuticlamp as claimed in claim 1, wherein said light diverting means comprisesa Brewster polarizer, said second obtuse angle being twice theBrewster's angle, said tubes being cut by a plane having a normalclosing Brewster's angle with both of said axes and said polarizercomprising a plurality of spaced glass plates attached to said tubesalong said cut plane.
 3. The therapeutic lamp as claimed in claim 2,wherein said filter plate (37) closes said second tube.
 4. Thetherapeutic lamp as claimed in claim 2, wherein said assembly isarranged in said middle and frontal portions so that said spacing aroundthe assembly is wider close to said polarizer than close to saidreflector.
 5. The therapeutic lamp as claimed in claim 1, wherein saidfirst obtuse angle amounts to between 105° and 120°.
 6. The therapeuticlamp as claimed in claim 1, wherein said handle has finger receivingdepressions at the outer perimeter facing to an opposite directionrelative to the mouth opening of said frontal portion.
 7. Thetherapeutic lamp as claimed in claim 6, wherein said slots (25) of saidhandle (25) are provided at the lower end thereof.
 8. The therapeuticlamp as claimed in claim 2, wherein said glass plates have ellipticalforms and a metal closing plate of the same form is provided which isspaced from the rear one of said glass plates and said closing plateabutting said cut plane of said tubes, and said closing plate beingblack at both sides.
 9. The therapeutic lamp as claimed in claim 2,wherein said bulb is a metal halogen bulb built together with saidreflector and being underheated in operation at most by 5%.